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    <div align="right">Last update : July 2000</div>
    <p>
      <b>nand2mean</b> -  difference of the means of
  two independent samples</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>[dif]=nand2mean(sample1,sample2)  </tt>
      </dd>
      <dd>
        <tt>[dif]=nand2mean(sample1,sample2,conf)  </tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
    </h3>
    <ul>
      <li>
        <tt>
          <b>sample1</b>
        </tt>real or complex vector or matrix</li>
      <li>
        <tt>
          <b>sample2</b>
        </tt>real or complex vector or matrix</li>
      <li>
        <tt>
          <b>conf</b>
        </tt>real scalar between 0 and 1</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
    This  function computes   an  estimate  (dif(1)) for   the
    difference of the means of two independent samples (arrays
    sample1  and sample2) and gives  the half amplitude of the
    range of variability of dif  with an indicated  confidence
    level (dif(2)). The choice of the normal or t fonctions as
    the  probability fonction depends on  the sizes of sample1
    and sample2.  We suppose that  the underlying variances of
    both populations are equal. NAN values are not counted.</p>
    <p>
    In Labostat, NAN values stand for missing values in tables.</p>
    <p>
    In absence of the confidence  parameter a confidence level
    of 95% is assumed.</p>
    <h3>
      <font color="blue">References</font>
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    <dl>
      <p>
    Wonacott,  T.H. &amp; Wonacott, R.J.; Introductory Statistics, 5th edition, J.Wiley &amp; Sons, 1990.</p>
    </dl>
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